1. Technical Field
This invention relates to an electronic component comprising a barrier layer of an advantageous composition. Such an electronic component can be part of an integrated electronic circuit.
2. Description of the Related Art
“Electronic component” is understood to mean any element based on an electrical and/or electronic circuit, active or passive, intended to be assembled with other electronic components in order to realize one or more electronic functions. Examples of active electronic components are transistors, diodes, and integrated circuits, and examples of passive electronic components are resistors, capacitors, coils, and filters.
“Barrier layer” is understood to mean a layer of material able to prevent, very substantially, the diffusion of a metal and/or of oxygen through it. Such layers are frequently implemented for electronic components. Non-limiting examples of barrier layers are layers used in transistor gates, for example to separate a layer of polysilicon from a conductive layer (for MOS or CMOS transistors for example), layers of material used as electrodes in capacitors (for example MIM (Metal-Insulator-Metal) capacitors or capacitors which are part of DRAM (Dynamic Random Access Memory)).
There is a desire to obtain low resistivities, particularly for applications such as electrodes.
Barrier layers currently in widespread use are, for example, composed of titanium nitride TiN. TiN barrier layers have, for example, a resistivity on the order of 500 μΩ·cm when they are deposited with an organometallic precursor. In general, the thickness of such a layer is on the order of several hundred Angstroms (Å). These are used in particular as a layer for preventing the diffusion of copper from a copper layer. They can generally be replaced by layers of TaN on Ta, depending on the type of integrated circuit.
It is advantageous if the TiN layers are used as electrodes in MIM capacitors.
It is known to deposit the TiN layers by various technologies where the decomposition of a precursor enables a deposition on a surface, particularly the technologies of physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD), or plasma-enhanced atomic layer deposition (PEALD). Examples of frequently used precursors include TiCl4 or TDMAT (tetrakis(dimethylamido)titanium).
In general, the TiN compound deposited is substantially stoichiometric (50% Ti-50% N, expressed in atomic %).
Although widely used, this solution has certain disadvantages.
In fact, a TiN diffusion barrier may have defects. For example, when TiN is layered on an oxide layer or a copper layer, significant diffusion of oxygen or copper respectively through the TiN layer can occur. One explanation is that such undesirable diffusion can be attributed to the structure of the deposited TiN, which is in the form of columns.